Fire Sprinkler Corrosion Prevention Systems are systems in which pipes are filled with pressurized nitrogen, rather than water. The nitrogen holds a remote valve, known as a dry pipe valve, in a closed position. Located in a heated space, the dry-pipe valve prevents water from entering the pipe until a fire causes one or more sprinklers to operate. Once this happens, the air escapes and the dry pipe valve releases. Water then enters the pipe, flowing through open sprinklers onto the fire. Nitrogen is used to prevent corrosion, more specifically, microbiologically influenced corrosion (MIC) in the piping system.